There has conventionally been a blasting apparatus for blasting a to-be-blasted object such as concrete or base rock by using discharge energy.
This blasting apparatus has a thin metal wire connecting electrodes to each other, a blasting substance (for example, water or oil is used) for transmitting pressure, which is filled in a blasting vessel and immerses the thin metal wire therein, and an energy supply circuit for supplying electrical energy to the thin metal wire via the electrodes.
The following is a description of a blasting method for blasting a to-be-blasted object such as base rock by using the blasting apparatus configured as described above.
First, a mounting hole is formed in the to-be-blasted object and a blasting vessel is mounted in this mounting hole. Next, electrical energy having been charged in a capacitor, which is a constituent element of the energy supply circuit, is discharged and supplied to the thin metal wire for a very short period of time. Thus, the thin metal wire is fused and vaporized rapidly so as to be expanded, and the expansion force of the thin metal wire is transmitted toward the outside by means of the blasting substance. The expansion force acts in the diametrical direction of the mounting hole, for example, against the wall surface of the mounting hole, thereby blasting the to-be-blasted object.
As described above, in the case where the to-be-blasted object is a base rock or the like, if the mounting hole is formed in the to-be-blasted object, and the blasting vessel is mounted in this mounting hole, the expansion force caused by the fusion and vaporization of the thin metal wire acts in the diametrical direction of the mounting hole, so that a sufficient impact force is given to the to-be-blasted object, and consequently the to-be-blasted object is blasted. In the case where the to-be-blasted object is a plate-shaped object, however, no mounting hole is formed in the to-be-blasted object, and the blasting vessel is merely caused to abut on the surface of the to-be-blasted object, so that almost all of the expansion force caused by the fusion and vaporization of the thin metal wire escapes into the air, and consequently a sufficient blasting force cannot be given to the to-be-blasted object.
Accordingly, an object of the present invention is to provide a blasting apparatus which solves the above problem.